linux-kernel - Re: rename probe_kernel_* and probe_user

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Message-ID: <CAHk-=wjpnu=882iD9ck9Ywt6R1LYX_Hv-oS7dBMsWZwDRGZ5jA@mail.gmail.com>
Date:   Thu, 18 Jun 2020 12:48:22 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Christoph Hellwig <hch@....de>,
        Russell King <linux@...linux.org.uk>,
        Tony Luck <tony.luck@...el.com>, Helge Deller <deller@....de>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        linux-ia64@...r.kernel.org, linux-parisc@...r.kernel.org,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        "the arch/x86 maintainers" <x86@...nel.org>
Subject: Re: rename probe_kernel_* and probe_user_*

[ Explicitly added architecture lists and developers to the cc to make
this more visible ]

On Wed, Jun 17, 2020 at 12:38 AM Christoph Hellwig <hch@....de> wrote:
>
> Andrew and I decided to drop the patches implementing your suggested
> rename of the probe_kernel_* and probe_user_* helpers from -mm as there
> were way to many conflicts.  After -rc1 might be a good time for this as
> all the conflicts are resolved now.

So I've merged this renaming now, together with my changes to make
'get_kernel_nofault()' look and act a lot more like 'get_user()'.

It just felt wrong (and potentially dangerous) to me to have a
'get_kernel_nofault()' naming that implied semantics that we're all
familiar with from 'get_user()', but acting very differently.

But part of the fixups I made for the type checking are for
architectures where I didn't even compile-test the end result. I
looked at every case individually, and the patch looks sane, but I
could have screwed something up.

Basically, 'get_kernel_nofault()' doesn't do the same automagic type
munging from the pointer to the target that 'get_user()' does, but at
least now it checks that the types are superficially compatible.
There should be build failures if they aren't, but I hopefully fixed
everything up properly for all architectures.

This email is partly to ask people to double-check, but partly just as
a heads-up so that _if_ I screwed something up, you'll have the
background and it won't take you by surprise.

               Linus